Low irritating detergent compositions

ABSTRACT

A liquid detergent composition exhibiting good cleansing characteristics and low ocular and skin irritancy comprising as the active ingredients a binary mixture of a sulfobetaine and an anionic detergent.

BACKGROUND OF THE INVENTION

The present invention relates to novel detergent compositions. Inparticular, it relates to liquid detergent compositions which exhibitrelatively low ocular and skin irritation and yet exhibit high foamvolume and improved foam stability resulting in good cleansingcharacteristics.

Detergent compositions, like most types of liquid cleaning agents,generally comprise a mixture of one or more surfactants as the activeingredient, perfumes, coloring agents, thickeners, and the like. Thesurfactants normally used in such compositions have two portions: (1) ahydrophobic hydrocarbon chain miscible with organic materials and (2) ahydrophilic end-group miscible with water. When such a surfactantcontacts a particle of soil, the hydrocarbon chains mix therewith andthe hydrophilic end-groups are presented to the aqueous solution. Thisprocess of emulsification allows the soil, which otherwise would resistremoval by the water, to be cleaned from the body thereby. Thesesurfactants may be classified as anionic, cationic, nonionic, oramphoteric, depending upon the character of the end-groups.

It is highly desirable that liquid detergent compositions exhibit highfoam volume and stability which result in good cleansingcharacteristics. Often, however, when compositions with suchcharacteristics are formulated, they are not mild and result in a highincidence of ocular and skin irritation which are undesirable,particularly when utilized by children. Other desirable characteristicsof liquid detergent compositions are good "slip" and easy rinsability."Slip" can be defined as the ability to easily spread over the areadesired to be cleansed.

Attempts to achieve compositions with such desirable characteristics arewell documented in the art, see e.g., U.S. Pat. Nos. 3,055,836;3,280,179; 2,999,069; 3,928,251 and the like, but these attempts haveusually failed to achieve the desired results. When good cleansingcompositions were formulated, they tended to result in high ocular andskin irritation and when such compositions exhibited low ocular and skinirritation they tended not to be good cleansing compositions.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide improved detergentcompositions.

It is another object of this invention to provide liquid detergentcompositions with good cleansing characteristics.

It is a further object of this invention to provide liquid detergentcompositions which exhibit good cleansing characteristics and low ocularand skin irritancy.

Other objects of this invention will be set forth in, or be apparentfrom, the following detailed description of the invention.

The foregoing objects and other features and advantages of the presentinvention are achieved by a detergent composition containing as theactive ingredients a binary mixture of surfactants. More specifically,the present invention relates to a liquid detergent compositioncontaining a binary mixture of a sulfobetaine and an anionic detergentas the active ingredients. The use of a mixture of these surfactants asthe active ingredients in the liquid detergent compositions of thepresent invention yields compositions with good cleansingcharacteristics and unexpected low ocular and skin irritancycharacteristics.

It has unexpectedly been found that the mixture of an anionic surfactantand a sulfobetaine at use levels which provide good cleansingcharacteristics result in lower ocular and skin irritation than ifeither of the surfactants were utilized alone at such levels to providethe cleansing characteristics. When the sulfobetaine or anionicsurfactant are utilized alone at levels to produce satisfactorycleansing, the ocular and skin irritancy is undesirable whereas when amixture of said surfactants are utilized at specific levels, the ocularand skin irritancy are significantly lower and within very acceptablelevels even for use by children.

DESCRIPTION OF PREFERRED EMBODIMENTS

A preferred embodiment of the present invention comprises a liquiddetergent composition containing a binary mixture of a sulfobetaine anda specific anionic detergent as the active ingredients.

The sulfobetaines useful in the present invention are of the formula:##STR1## wherein R is an alkyl group of from 8 to 18 carbon atoms ormixtures thereof; R' is OH or H; x is an integer from 1 to 3; and M isselected from alkali metals such as lithium, sodium or potassium,akaline earth metals such as magnesium and calcium, and alkanol aminesalts such as the mono-, di-, or triethanolamine salts.

A preferred sulfobetaine is one of the formula: ##STR2## wherein R is analkyl group containing 12 carbon atoms or a mixture of alkyl groupscontaining from 12 to 18 carbon atoms.

The sulfobetaine comprises about 1-15% by weight of the totalcomposition, preferably about 2-6% by weight, provided, however, thatthe total amount of sulfobetaine and anionic surfactant is not greaterthan about 20% by weight of the detergent composition. If less thanabout 1% by weight of the sulfobetaine is utilized, the resultingdetergent composition will not foam and clean satisfactorily; and ifgreater than about 15% of the sulfobetaine is utilized, eye irritationis undesirably increased and such is also economically unfeasible.

The anionic detergents useful in the present invention are the alkylether sulfates of the formula:

    R"--O--(C.sub.2 H.sub.4 O).sub.x --SO.sub.3 --M

wherein R" is a branched or straight chain saturated or unsaturatedaliphatic hydrocarbon radical, alkylaromatic hydrocarbon radical oralkylaryl hydrocarbon radical having from 6 to 20 carbon atoms; x is aninteger from 1-5 and M is selected from alkali metals such as lithium,sodium or potassium; alkaline earth metals such as magnesium andcalcium, and alkanolamine salts such as the mono-, di-, ortriethanolamine salts.

A preferred anionic detergent is one of the formula:

    R"--O--(C.sub.2 H.sub.4 O).sub.4 --SO.sub.3 Na

wherein R" is a branched chain aliphatic hydrocarbon radical having 13carbon atoms.

The anionic detergent comprises about 1-15% by weight of the totalcomposition, preferably about 2-6% by weight, provided, however, thatthe total amount of anionic surfactant and sulfobetaine is not greaterthan about 20% by weight of the detergent composition. If less thanabout 1% by weight of the anionic surfactant is utilized, the resultingdetergent composition will not foam or clean satisfactorily; and ifgreater than about 15% is utilized, eye and skin irritation isundesirably increased.

To achieve the desired results of this invention, the sulfobetaineshould be utilized in a weight ratio of 3:1 to 1:3 to the anionicdetergent, preferably in a weight ratio of about 1:1.

Thus, the liquid detergent composition of the invention comprises fromabout 1% to about 15% by weight of sulfobetaine and from about 1% toabout 15% by weight of anionic surfactant based upon the weight of theentire composition, but the total of the active ingredients is notgreater than 20% by weight of the entire composition. The remainder ofthe composition is essentially water, but it may also containthickeners, dyes, perfumes, antibacterial agents, preservatives, pHadjusters, and the like, as desired. The preferred compositions of theinvention comprise about 2% to about 6% by weight of sulfobetaine andfrom about 2% to about 6% by weight of anionic surfactant based on theweight of the entire composition.

The liquid detergent compositions of the invention are prepared bymixing the sulfobetaine and the anionic surfactant together with a smallamount of deionized water, preferably at ambient temperature, to form amixture, and a thickener (if desired) is mixed in. Elevated temperaturesmay be employed at this stage to promote easier mixing of theingredients. Then additional deionized water is mixed in to bring theweight of the composition to about three-quarters of its final weight,and the pH is adjusted to from about 5.0 to 8.0, preferably about6.5-7.0 by addition of a mineral acid (e.g., hydrochloric acid) or asolution of a strong base (e.g., sodium hydroxide). Finally, theremainder of the deionized water is added and the pH is again adjustedwithin the desired range. Other ingredients such as preservatives, dyes,perfumes, skin conditioning agents, emollients, and the like may beadded in any of the last three steps.

Specific embodiments of the present invention are illustrated by thefollowing examples. It will be understood, however, that the inventionis not confined to the specific limitations set forth in the individualexamples, but rather to the scope of the appended claims. All parts areby weight unless indicated otherwise.

EXAMPLE I

A liquid detergent cleansing composition is prepared by charging 500lbs. of deionized water to a stream jacketed vessel and 0.5 lbs. of a.[.thickener.]. .Iadd.chelating agent.Iaddend., Versene 100 withagitation. 111.0 lbs. of a 44% active solution of a sulfobetaine of theformula: ##STR3## wherein R is a mixture of alkyl groups containing from12 to 18 carbon atoms,

and 156.3 lbs. of a 32% active solution of a alkyl ether sulfate of theformula:

    R"--O--(C.sub.2 H.sub.4 O).sub.4 --SO.sub.3 Na

wherein R" is a branched chain aliphatic hydrocarbon radical having 13carbon atoms,

are then added and the resulting mixture is then heated to 50°-60° C.15.0 lbs. of a thickener, polyethylene glycol distearate are added andagitation is provided until the mixture is clear and then .[.128.0.]..Iadd.5.00 .Iaddend.lbs. of an emollient, Arlamol E, are added.[.followed by the addition of 211.75 lbs. of deionized water.].. Themixture is then cooled to 40° C. and 1.0 lb. of a preservative, Dowicil200, 3 lbs. of benzyl alcohol, 0.75 lbs. of fragrance are added followedby the addition of 5.0 lbs. of phosphoric acid and 20 lbs. of aphosphate buffer solution to adjust the pH to about 6.8 .Iadd.andsufficient deionized water is added to bring the total change to 1000lbs.Iaddend.. The resulting solution is cooled with agitation to roomtemperature and consists of the following ingredients:

    ______________________________________                                                            %                                                         ______________________________________                                        .[.32% active solution.].                                                                           .[.4.06.]..Iadd.5.00.Iaddend.                           alkyl ether sulfate                                                           Ariamol E             .[.12.8.]..Iadd.0.50.Iaddend.                           ICI/Americas Inc.                                                             tradename for polyoxyporpylene (15)                                           stearyl ether                                                                 .[.44% active solution.].                                                                           4.88                                                    sulfobetaine                                                                  phosphate buffer      2.0                                                     polyethylene glycol   1.5                                                     6000 distearate                                                               fragrance             0.075                                                   Versene 100           0.05                                                    Dow Chemical Company's                                                        tradename for                                                                 ethylene diamine                                                              tetrasodium acetate                                                           phosphoric acid       .[.0.05.]..Iadd.0.50.Iaddend.                           benzyl alcohol        .[.0.03.]..Iadd.0.30.Iaddend.                           Dowicil 200           .[.0.01.]..Iadd.0.10.Iaddend.                           Dow Chemical Company's                                                        tradename for the                                                             cis isomer of                                                                 1-(3-chloroalkyl)-3,5,7-                                                      triaza-1-azoneaadamantine                                                     chloride                                                                      deionized water       q.s to 100%                                             ______________________________________                                    

The liquid detergent cleansing composition of this example is tested forocular irritation by the following modified Draize test (see J. H.Draize et al., Toilet Goods Associations #17, May, 1952, #1 Proc. Sci.Sect.):

A 1 ml. sample of the neutral composition under test is dropped into oneeye of each of six rabbits. Daily administration of the same quantity ofeach of the samples is continued for 3 consecutive days. Observationsare recorded after one hour, one day, two days, three days, four daysand seven days after samples are dropped into the eyes. The extremes ofthe results either show substantially no change or show only a slightirritation (foreign body effect) in the appearance of the rabbit's eyesafter seven days, or severe irritation or complete corneal opacity, asthe case may be.

The composition prepared in Example I is tested by this procedure andfound to be only a very slight irritant a.

The liquid detergent cleansing composition of this example is tested forfoam volume and stability as measured by the following modification ofthe well-known Ross-Miles foam test ["Oil and Soap", 18, 99-102 (1941)]:

Lanolin, anhydrous, cosmetic grade is mixed with dioxane (technicalgrade) in the proportion of 2.5 grams lanolin and 100 grams of dioxane.The lanolin is first mixed with 25 cc. of dioxane. This mixture isheated over a steam bath to 45° C. in order to dissolve the lanolin inthe dioxane. The remainder of the dioxane is then added and mixed. Thislanolin-dioxane solution, which is stored in an amber bottle, should beprepared fresh on the day that the tests are run.

The composition to be tested is diluted by adding 376 cc. of distilledwater to 4 grams of the composition, and then by adding 20 cc. of thelanolin-dioxane solution described above while mixing. Heat is producedwhen the lanolin-dioxane solution is added to the solution of thecomposition in water and care must be taken in adjusting the temperatureof this solution to 24°-25° C. Both of these intermediate solutionsshould therefore be adjusted to 23° C. before mixing. The cooling of thelanolin-dioxane solution should be gradual in order to avoidprecipitation of the lanolin. This will produce a final solution with atemperature of 24°-25° C.

The final solution of the composition to be tested, water, dioxane andlanolin described above, is then run in a modified Ross-Miles foamcolumn in the usual way. All tests are conducted in duplicate, and theaverage of the two results is taken. Foam stability is determined bymeasuring the decay in foam height after five minutes, expressed as apercentage of the original height.

The detergent composition of this example possesses a high foam volumeand significantly superior foam stability when compared to a leadingcommercial personal cleansing product as demonstrated by the followingresults:

    ______________________________________                                                     Foam Volume (MM)                                                                           % Decay                                             ______________________________________                                        Composition of Example I                                                                     180            17.0                                            Commercial Product                                                                           175            85.0                                            ______________________________________                                    

EXAMPLES II-V

Liquid detergent cleansing compositions consisting of the followingingredients are prepared in accordance with the procedure of Example I:

    ______________________________________                                                       % W/W                                                                         Example                                                                       II    III     IV      V                                        ______________________________________                                        sulfobetaine of Example I                                                                      4.950   1.000   5.000 15.000                                 alkyl ether sulfate of                                                                         4.096   1.000   15.000                                                                              5.000                                  Example I                                                                     phosphate buffer 2.000   2.000   2.000 2.000                                  deionized water  q.s. to q.s. to q.s. to                                                                             q.s. to                                                 100     100     100   100                                    ______________________________________                                    

These compositions all exhibit low ocular and skin irritation andexcellent foam stability.

EXAMPLES VI-VII

Liquid detergent cleansing compositions consisting of the followingingredients are prepared in accordance with the procedure in Example I:

    ______________________________________                                                        % W/W                                                                         Example                                                                       VI        VII                                                 ______________________________________                                        sulfobetaine of Example I                                                                       9.046       --                                              alkyl ether sulfate of Example I                                                                --          9.046                                           phosphate buffer  2.000       2.000                                           deionized water   q.s. to 100 q.s. to 100                                     ______________________________________                                    

The compositions of Examples II, VI and VII are tested for eyeirritation by means of the modified Draize test described in Example Iabove and the results are reported in Table 1 below:

                  TABLE 1                                                         ______________________________________                                        Composition   Eye Irritancy Score                                             ______________________________________                                        Example II    11.3                                                            Example VI    47.0                                                            Example VII   12.0                                                            ______________________________________                                    

As can be readily seen from the results in Table 1, the composition ofExample II containing the sulfobetaine and alkyl ether sulfatedemonstrated an unexpected lower eye irritancy score than either thecomposition of Example VI (sulfobetaine alone) or Example VII (alkylether sulfate alone) even though the total concentration of activesurfactant ingredients in each of the compositions is about the same.This demonstrates a synergistic reduction in eye irritancy with thecombination of surfactants of the compositions of the present inventionas well as providing good cleansing characteristics.

In addition to the preferred embodiments described herein, otherembodiments, arrangements and variations within the spirit of theinvention and the scope of the appended claims will occur to thoseskilled in the art.

What is claimed is:
 1. A low irritating liquid detergent compositionwherein the active ingredients consist essentially of:(a) from about 1to 15% by weight of the total composition of a sulfobetaine of theformula ##STR4## wherein R is an alkyl group of from 8 to 18 carbonatoms or mixtures thereof, R' is OH or H, x is an integer from 1 to 3and M is selected from the group consisting of alkali metals, alkalineearth metals and alkanol amine salts selected from the group consistingof mono-, di- and triethanolamine salts; and (b) from about 1 to 15% byweight of the total composition of an anionic detergent of the formula

    R"--O--(C.sub.2 H.sub.4 O).sub.x --SO.sub.3 M

wherein R" is a branched or straight chain saturated or unsaturatedhydrocarbon radical, alkylaromatic hydrocarbon radical or alkylarylhydrocarbon radical containing from 6 to 20 carbon atoms, x is aninteger from 1 to 5 and M is selected from the group consisting ofalkali metals, alkaline earth metals and alkanol amine salts; whereinthe total of (a) and (b) does not exceed about 20% by weight of thetotal composition.
 2. The composition of claim 1 wherein the anionicdetergent is present in an amount of from about 2 to 6% by weight of thetotal composition.
 3. The composition of claim 1 wherein thesulfobetaine is present in an amount of from about 2 to 6% by weight ofthe total composition.
 4. The composition of claim 1 wherein the anionicdetergent is of the formula

    R"--O--(C.sub.2 H.sub.4 O).sub.4 --SO.sub.3 Na

wherein R" is a branched chain aliphatic hydrocarbon radical containing13 carbon atoms.
 5. The composition of claim 1 wherein the sulfobetaineis of the formula ##STR5## wherein R is an alkyl group containing 12carbon atoms or a mixture of alkyl groups containing from 12 to 18carbon atoms.
 6. The composition of claim 2 wherein the sulfobetaine andanionic detergent are present in a weight ratio of about 1:1.
 7. Thecomposition of claim 1 wherein the sulfobetaine and anionic detergentare present in a weight ratio of from about 3:1 to about 1:3.